ST. PETERSBURG, Russia -- Ukrainian astronomers say an asteroid might collide with Earth in a couple of decades, a Russian news service reported Thursday.

Space watchers from the observatory in the Crimean peninsula said they discovered an asteroid about 1,345 feet in diameter, which they call 2013 TV135, that is approaching Earth at a potentially dangerous trajectory, RIA Novosti said.

The astronomers calculated the date of a potential collision as Aug. 26, 2032, the news service said, but they acknowledged the odds of an impact as 1 in 63,000.

The force of such a possible collision could be the equivalent of setting off about 2,500 megatons of TNT, RIA Novosti reported.

The discovery, which was made Saturday, was confirmed by two Russian observatories and by Italian, British and Spanish astronomers, RIA Novosti reported.

"A 400-meter asteroid is threatening to blow up the Earth,” Russian Vice Premier Dmitry Rogozin, in charge of his nation's space research, wrote Wednesday on his Twitter account. “Here is a super target for the national cosmonautics.”

[Updated at 12:32 p.m. on Oct. 17: For at least the next 50 years, humans will be incapable of protecting Earth against meteors and asteroids, predicted Igor Korotchenko, a Russian senior defense expert.

“We, humankind, can intercept missiles and planes manufactured by man, but our radars and missiles are helpless against asteroids, as they travel at faster speeds of dozens of miles per second, they have different trajectories and they can be much, much bigger than strategic missiles we are dealing with today," said Korotchenko, editor in chief of the National Defense journal. "How can you intercept or even avert anything coming vertically down at us from outer space [and hundreds of feet] in diameter?”]

Meanwhile, divers working Wednesday in Chebarkul Lake in Russia's Ural Mountains raised what could be a large piece of the meteor that exploded over the region in February.

That strike from space caused some damage and injuries to hundreds of people, mainly from shattered window glass.

[For the record at 12:32 p.m. on Oct. 17: The headline on an early version of this post incorrectly identified the astronomers as Russian. They are Ukrainian. And the possible collision of the asteroid with Earth would be the equivalent of setting off about 2,500 megatons of TNT, rather than the 2.5 megatons earlier reported.]